A spectrum is a valuable resource, and a radio communication system is engaged in introducing more complicated technologies to improve use efficiency of the spectrum, including time-division multiple access (TDMA), code-division multiple access (CDMA), orthogonal frequency division multiplexing (OFDM), and new encoding and decoding. Subsequent introduction of a multi-antenna multiple-input multiple output (MIMO) system and technologies such as joint processing of multiple cells improve the use efficiency of the spectrum. For the use of the spectrum in a current radio communication system, a duplex manner is divided into modes such as time division multiplexing (TDD), frequency division multiplexing (FDD), and half-duplex FDD (H-FDD), that is, it is separated in a frequency domain, or separated in time to perform receiving and sending, which cannot implement receiving and sending at a same frequency or same time, that is, the full-duplex mode. In addition, due to a path loss of air interface transmission of a radio signal, in a same node the transmitting power of a transmitted signal at an antenna port is far greater than that of a received signal from another node in distance, thereby leading to problems that a receiver is blocked, a sampling bit-width and a dynamic range of a signal after analog-to-digital conversion (ADC) are limited, or a signal-to-noise ratio is too low to demodulate a correct signal, and a system cannot work normally. Therefore, in normal circumstances, the full-duplex communication cannot work normally by using duplex modes such as the FDD and the TDD.
In the prior art for implementing full-duplex communication (performing receiving and sending at a same frequency and same time), usually two transmitting antennas and one receiving antenna are adopted. The distance between the two transmitting antennas and the receiving antenna is adjusted, and null elimination is formed at a receiving port, thereby achieving an effect of elimination of an interfering signal around 30 decibels (dB) coupled from a transmitting channel to a receiving channel. Further, through an interference elimination component in an analog domain and by eliminating the interfering signal in a digital domain, a 30 to 35 dB interfering signal coupled by a transmitting channel signal may be eliminated. However, problems such as high requirements on the number of antennas and position accuracy, a limited interfering signal elimination effect, and a high cost still exist.